Electromagnetic counter

ABSTRACT

In an electromagnetic counter of the type including an electric coil responsive to a signal to be counted, a counter operated by the coil, a holding contact which is closed when the coil is energized and adapted to hold itself closed and any related circuit in the operating condition, and means for resetting the counter and opening the holding contact, the holding contact is comprised by a magnetic switch disposed to be operated by the coil and the reset means comprises a permanent magnet which is normally positioned with respect to the magnetic switch such that the magnetic flux generated by the permanent magnet is not sufficient to close the magnetic switch but sufficient to hold the magnetic switch in the closed state once it has been closed by the coil.

I Unlted States Patent 11 1 1111 3,838,253 Sanada Sept. 24, 1974 ELECTROMAGNETIC COUNTER 3,292,121 12/1966 Bergstrasser 335/153 [75] Inventor: JNgmrzgloshi Sanada, Urawa City, Primary Examiner Raulfe B. Zache p Assistant Examiner--Robert F. Gnuse [73] Assignee: Tamura Electric Works, Ltd., Attorney, Agent, or FirmDike, Bronstein, Roberts,

Tokyo, Japan Cushman & Pfund 22 F] d: 14 1 72 1 June 9 57 ABSTRACT [211 App! 26248l In an electromagnetic counter of the type including an electric coil responsive to a signal to be counted, a [30] Foreign Application Priority Data counter operated by the coil, a holding contact which June 29 1971 Japan 46-55860 is Closed when the Coil is energized and adapted to hold itself closed and any related circuit in the operat- [52] CL 235/92 C 23 5 /92 R 235/92 K ing condition, and means for resetting the counter and 335/153 opening the holding contact, the holding contact is 51 Int. Cl. H03k 23/03 eemprieed by a magnetie Switch disposed to be Oper- [58] Field of Search 235/92 0, 92 K; 317/150, eted by the and the reset means eempriees P 317/154; 335 H 53 manent magnet which is normally positioned with respect to the magnetic switch such that the magnetic [56] References Cited flux generated by the permanent magnet is not sufficient to close the magnetic switch but sufficient to UNITED STATES PATENTS hold the magnetic switch in the closed state once it 3,158,761 11/1964 Bullock 317/154 has been closed by the coil 3,204,869 9/1965 Zomkeller 235/92 C 3,227,838 1/1966 1 Claim, 2 Drawing Figures Hoeppel 335/153 ELECTROMAGNETIC COUNTER BACKGROUND OF THE INVENTION This invention relates to an electromagnetic counter and more particularly to an electromagnetic counter provided with an electric contact for holding itself closed and any related circuit in the operating state from the commencement to the termination of the counting operation.

As is well known in the art, electromagnetic counters are used in many applications such as an automatic control panel and a counter for counting the number of products. Where such electromagnetic counters are used for operating various control devices and gate circuits, it is necessary to provide an electric contact for holding itself closed and any related circuit in the operating condition from the commencement to the termination of the counting operation. The prior art electromagnetic counter with such a holding contact has a construction as shown in FIG. 1, for example. More particularly, the electromagnetic counter comprises an electrical coil A mounted on a base C, an armature B operated by electrical coil A and a contact operating member D operated by the free end of the armature. The contact operating member D is adapted to engage with one of a pair of resilient contact members E and E which are anchored to the base at their bases. The contact operating member D is provided with a lug F adapted to operate the reset member H of a digit wheel G. When operated, the reset member H resets the digit wheel G to zero. When a first signal to be counted is sent to coil A, armature B is disengaged from contact operating member D whereby the member D is snapped by the resiliency of contact member E thus closing contacts E and E Accordingly, these contacts are held in their closed state irrespective of the second and following signals and are opened only when a zero reset button I is depressed for restoring the contact operating member D to the original position shown in FIG. 1 by depressing zero reset member H. However, the electromagnetic counter of the construction described above is not advantageous in that not only its construction is complicated but also the response of the digit wheel G for the first and second and succeeding signals to be counted becomes different redue to the resistance imposed upon the armature B by the contact operating member D. Accordingly, the counter can not operate stably. For this reason the prior art electromagnetic counter has been designed to require excessively large pulses and to produce ample flux density by the coil in order to prevent misoperation. However, under a certain condition it is impossible to provide sufficiently large signals. Further it is necessary to increase the dimension of the coil for producing magnetic flux of large density.

SUMMARY OF THE INVENTION Accordingly it is an object of this invention to provide an improved electromagnetic counter of simple construction and which does not increase the load of the operating coil or armature due to the provision of the holding contact and which can operate stably in response to any signal to be counted.

According to this invention there is provided an electromagnetic counter of the type including an electric coil responsive to a signal to be counted, a pair of digit wheels operated by the coil, a holding contact which is closed when the coil is energized and adapted to hold itself closed and any related circuit in the operating condition, and means for resetting the digit wheels and opening the holding contact, characterized in that the holding contact comprises a magnetic switch disposed to be operated by the coil and the reset means comprises a permanent magnet which is normally positioned with respect to the magnetic switch such that the magentic flux generated by the permanent magnet is not sufficient to close the magnetic switch but sufficient to hold it in the closed state once it has been closed by the coil.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing:

FIG. 11 is a diagrammatic representation of a prior art electromagnetic counter with holding contacts and FIG. 2 is a similar view of an electromagnetic counter embodying the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference now to FIG. 2, there is shown a twin type electromagnetic counter embodying the invention. The electromagnetic counter shown therein comprises a pair of digit wheels 2 and 3 with their shafts 4 and 5 journalled in the front portion of a base ll. Digit wheels 2 and 3 are coupled together by means of an intermediate gear 6. On the lower rear side of base 1 is mounted an electric coil 8 associated with a magnetic yoke 7 and a magnetic core 9. An armature 10 is attracted by magnetic core 9 and the lower end of the armature 10 is pivotally supported by the yoke 7. The armature 10 carries a lever 11 and a pawl 13 is mounted on the outer end of lever 11 for operating-a ratchet wheel 12 provided for one digit wheel 2. When the coil 8 is energized by a signal to be counted, the armature 10 is attracted by core 9 to advance one step the digit wheels 2 and 3 by pawl 13. In other words, the application of the signals causes digit wheel 2 to advance one step in the addition direction and digit wheel 3 to rotate one step in the subtraction direction. According to this invention, a magnetic responsive element shown as a reed switch 14 is disposed in parallel with core 9 at a position influenced by the magnetic flux generated by coil 8. As above described, the output of reed switch 14 is used to operate the gate circuits of various control devices.

The inner end 15a of a zero reset member 15 for resetting to zero digit wheels 2 and 3 is disposed to extend substantially in parallel with reed switch 14 and a permanent magnet 16 is secured to the inner end 15a. The position of the permanent magnet 16 and the intensity of the magnetic flux produced thereby are selected such that the magnetic flux is not sufficient to operate the reed switch but sufficient to hold it in the operated state. The zero reset member 15 is provided with an integral reset lug 17 for engaging a heart shaped cam (not shown) associated with digit wheel 3 thereby resetting digit wheels 2 and 3 to zero.

As above described, the reed switch 14 is positioned to be influenced by the magnetic flux generated by permanent magnet 16 but the reed switch 14 will not be operated by this flux alone because the effect of the magnetic flux is small. When a first signal to be counted is applied to coil 8, the reed switch 14 will be closed due to leakage flux from coil 8. Once closed, the reed switch 14 is held in its operated state by the flux generated by permanent magnet 16 irrespective of the subsequent deenergization of coil 8. When the zero reset member 15 is operated later, the permanent magnet 16 is moved away from reed switch 14 thus opening the same.

As above described, provision of reed switch 14 acting as the holding contact does not affect the sensitivity of the armature so that it is possible to operate the coil with smaller power than the prior art design. In other words, the invention provides an electromagnetic counter of small and compact construction.

While the invention has been shown and described in terms of a preferred embodiment it will be clear that the invention is by no means limited to this particular embodiment and that many changes and modification will readily occur to one skilled in the art without departing from the true spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. An electromagnetic counter comprising an electric coil adapted to be energized by a signal to be counted, an armature actuated by said coil, digit wheel means operated by said armature to count successive energizations of said coil, a holding contact in the form of a magnetic reed switch disposed to be operated by the leakage flux of said coil, reset means movable to reset said counter, a permanent magnet mounted to move with said reset means and normally positioned with respect to said magnetic reed switch such that the magnetic flux generated by said permanent magnet is not sufficient to close said magnetic reed switch but sufficient to hold said magnetic reed switch in the closed state once it has been closed by said coil, said flux of said permanent magnet being insufficient to hold said magnetic reed switch in a closed state when said permanent magnet is displaced from said normal position by movement of said reset means, the contact of said reed switch being adapted to serve as holding contacts during operation of said counter which are opened only by movement of said reset means. 

1. An electromagnetic counter comprising an electric coil adapted to be energized by a signal to be counted, an armature actuated by said coil, digit wheel means operated by said armature to count successive energizations of said coil, a holding contact in the form of a magnetic reed switch disposed to be operated by the leakage flux of said coil, reset means movable to reset said counter, a permanent magnet mounted to move with said reset means and normally positioned with respect to said magnetic reed switch such that the magnetic flux generated by said permanent magnet is not sufficient to close said magnetic reed switch but sufficient to hold said magnetic reed switch in the closed state once it has been closed by said coil, said flux of said permanent magnet being insufficient to hold said magnetic reed switch in a closed state when said permanent magnet is displaced from said normal position by movement of said reset means, the contact of said reed switch being adapted to serve as holding contacts during operation of said counter which are opened only by movement of said reset means. 